We tried to find out the cytotoxic and anticancer property of methanolic extract of <I>N. sativa</I> seeds against prostate cancer cells (PC3). A concentration range of extract (100-0.01 ÃŽÂ¼g mL<SUP>-1</SUP>) in culture medium (DMEM) was tested. Inhibition of colony formation was studied and microscopic observations of stained colonies were performed. Colony inhibition at highest concentration (100 ÃŽÂ¼g mL<SUP>-1</SUP>) was 87.097% and at lowest concentration (0.01 ÃŽÂ¼g mL<SUP>-1</SUP>) it was 54.105. IC<SUB>50 </SUB>was <0.01 ÃŽÂ¼g mL<SUP>-1</SUP>. Microscopic observation confirmed karyolysis, karyorrhexin and picnosis in treated cells as well as presence of characteristic morphological changes associated with apoptotic cells like blebs, blisters and echinoid spikes etc. on cell membrane. These findings advocate that methanolic extract of <I>N. sativa</I> seeds is a potent clonoigenic inhibitor of PC3 cell and cell deaths might have taken place through apoptosis. However exact mechanism for apoptosis can not find out from this study but study may help in searching new effective medicine for prostate cancer therapy.